Posted: September 13th, 2017

Case Study Assessment

Case Study Assessment
As part of the assessment for this module you are required to answer
the questions below in sentence and paragraph form, showing your
knowledge of the regulation of the body systems, supporting your
answers where possible with evidence drawn from the research
literature. The total marks available will be divided equally between the
questions. You may illustrate your answers with appropriate diagrams
or figures taken from original papers. All original papers and reviews
should be properly cited in the text and included in a list of references
at the end of your script. If you have used a textbook or textbooks for
basic, background information provided in your answers, your source/s
should be indicated. The world limit for the text of your answers (minus
Figures and references list) is 3-3500 words.
Case questions
Endurance exercise presents considerable challenges to the major
body systems, particularly when undertaken in high environmental
temperatures. The athlete may take several different measures before
and during endurance exercise to improve performance and to avoid
untoward consequences. However, despite these precautions, the
athlete may experience a variety of different problems ranging from
unpleasant to life threatening.
1. When exercise is performed at >70%VO2max in a high ambient
temperature ( = 35oC), ventilation (VE) is higher at any given
workload than when it is performed in a moderate temperature of
?16oC.
i. What mechanisms might underlie this effect? On the
basis of recent evidence, which is/are the more likely to
be important?
ii. On the basis of what is known of how different
physiological mechanisms adapt in high environmental
temperatures (eg sweating, cutaneous vasodilatation),
how might you expect exposure to a high ambient
temperature over 10 days or so, to affect the ventilatory
response to exercise in an athlete who competes in
high ambient temperatures? Explain your answer. How
would you test your proposals? Is the change you
propose likely to be an advantage or disadvantage to
performance? Explain your answer.
2. When exercise is performed at >70%VO2max in a high ambient
temperature with adequate hydration, muscle lactate
accumulation and venous plasma lactate concentration have
been shown to be higher than when exercise is performed at the
same intensity in a moderate temperature.
i. On the basis of the available evidence, are these
effects likely to be due to changes in the cardiovascular
response to exercise, or to changes in metabolism?
3. When exercise is performed at >70%VO2max in a high ambient
temperature, but without adequate hydration, the cardiovascular
response to exercise is compromised and fatigue occurs earlier.
Typically the athlete shows a smaller increase in cardiac output,
arterial blood pressure gradually falls and the increase in leg
muscle blood flow is reduced.
i. Discuss the reflex mechanisms that may contribute to
these cardiovascular changes. What are the most likely
explanations for the earlier fatigue and which is most
likely on the basis of current evidence?
4. At most marathon events, supplies of water and “sports” drinks
are provided in intervals along the route. Some runners take the
opportunity to drink at regular intervals, to avoid dehydration.
Others throw bottles of water to avoid overheating.
Measurements made at the end of such races have shown that a
substantial number of runners had a plasma sodium level of
<135mmol/L and in some, plasma sodium feel further after the
race. Some of these runners had maintained body weight, or
even gained body weight during the race. Nausea during and
after the race was common; some vomited after the race; many
complained of headache.
i. On the basis of available evidence, what is the most
likely explanation for the adverse changes during the
event ie nausea, headache etc? How would the kidney
deal with this situation? How many sympathetic and
hormonal influences on renal function contribute to the
outcome?
ii. On the basis of published evidence, what is the most
likely explanation for the further fall in plasma sodium
after the race?
5. The traditional view has been that a high carbohydrate diet is the
best preparation for endurance exercise so that intramuscular
stores of glycogen are maximized. However more recently it has
been argued that adding more fat to the diet can improve
performance and limit fatigue, providing carbohydrate intake is
maintained at 35-40% of total calories.
i. If you were designing a study to test whether any
improvement in performance on such a high fat diet
were due to increased fat oxidation, what types of
evidence could you look for and what measurements
might you make?
ii. How would you expect muscle fibre type and
composition of the individual to affect fat oxidation
during endurance exercise?
6. Athletes who have a complete spinal transection between
thoracic levels 3 and 5 rely on their upper body musculature foe
wheel chair endurance events. They have no motor control of
muscles below the lesion and no sensory feedback from these
regions to the brain.
i. How would you expect the cardiac response (heart rate
and stroke volume) to exercise at >70%VO2max in these
athletes to differ from that of an able bodied athlete.
Use the available evidence to support your answer.
ii. On the basis of current evidence, how would you expect
this level of spinal cord lesion to affect the ability of the
athlete to maintain body temperature when the event
takes place in high ambient temperatures?